Oil well circulation device



April 21, 1964 w. H. COOPER ETAL 3,129,762

OIL WELL CIRCULATION DEVICE Filed June 15, 1960 LIA V I ///l l// l// I l/I/ll/I/I/l III/I I ALIV/ WARREIY E. COOPER GERALD m. cOoPER INVENTORS BY Co,m*

ATTORNEY United States Patent Office 3,129,762 Patented Apr. 21, 1964 3,129,762 011. WELL CIRCULATION DEVICE Warren H. Cooper, Midland, Tex. (Odessa, Tex.), and Gerald M. Cooper, Midland, Tex. Filed June 13, 1960, Ser. No. 35,600 1 Claim. (Cl. 166-117) This invention relates to the art of well drilling and more particularly, to -a device for controlling the circulation of fluids in bore holes.

Frequently, in the course of drilling holes in the earths crust, such as in the search of oil and gas, with conventional rotary drilling equipment, penetration of porous fractured, or cavernous strata of rock results in thief zones which cause the loss of drilling fluid to varying degrees. In severse cases of lost circulation, complete loss of returns is experienced. Such a condition is particularly critical if allowed to continue, in that the hole or bore is not cleaned of cuttings and results in the eventual sticking of the drilling string. Further, control of high pressure zones is not possible due to the absence of the normal hydrostatic column of fluid.

Priorly, such zones of lost circulation have been plastered by the addition to the drilling fluid at the earths surface, of circulation control material such as fiber, cellophane flakes, cottonseed hulls, and so forth. In introducing such material at the surface, the material must travel through the slush pump, down the drilling string, and through the bit nozzles from which it is circulated to the fracture or cavernous thief zone. Introduction of the circulation control material at the surface requires that the material employed be sufliciently small to pass through the small restrictions and orifices found in the drilling string before it reaches the thief zones. In severely fractured or cavernous zones, the small-size circulation control material is ineffective in bridging or plastering the zone into which the bore hole fluid is passing. Often in less severe thief zones, excessive quantities of fine circulation control material are used to accomplish the desired bridging effect. These quantities are greater than would be necessary if larger pieces of circulation control material had been introduced. As mentioned above, however, the introduction of larger particles is not possible according to existing practices.

It is an object of this invention to provide a circulation control device for a bore hole which is a container into which large particles of circulation controlling material are inserted.

It is another object of this invention to employ as a bore hole circulation control device a frangible container of large-sized circulation control material, which container is fractured in the bore hole by the drill bit.

It is another object of this invention to provide as a circulation control device for a bore hole, a frangible container having an overall specific gravity greater than unity, which is filled with large particles of circulation control material.

Briefly, in accordance with aspects of this invention, a circulation control device is defined by a frangible container in which is enclosed large pieces of circulation control material. This material may be rags, coarsely ground wood chips, fiber, slugs of cottonseed hulls, or other materials which would be too large to permit introduction to the bore hole at the surface. The size of these pieces of material would prevent their use as circulation control material in a conventional manner. Advantageously, this control device may be fabricated from a lightweight frangible shell or case, one end of which is defined by a weighted nose piece, preferably tapered, and the other end which is enclosed by a frangible cap. Also advantageously, the control device is provided with a number of pressure equalizing apertures to permit the drilling fluid to enter the device and to permit the escape of air from the case. In its preferred embodiment, the device is defined by a laminated cylindrical shell, a conical nose at one end of the shell, which nose is preferably of a heavy material such as cement, a frangible cap at the other end of the cylinder, and the device is filled with circulation controlling material such as rags,'-wood chips, fiber, slugs of cottonseed hulls, or other materials. The specific gravity of the overall device is greater than unity so that the device will sink to the bottom of the bore hole. After the device has been inserted into the bore hole, the drill bit and attached drill string are inserted in the bore hole and lowered into engagement with the circulat-ion control device. Operation of the drill bit then fractures the control device, permitting the circulation control material to block the passages in the thief zones or zones of lost circulation.

These and various other objects and features of this invention will be more clearly understood from a reading of the detailed description of the invention in conjunction with the drawing in which:

FIGURE 1 is a view in elevation of one illustrative embodiment of this invention;

FIGURE 2 is a view in section taken along the lines 2 2 of FIGURE 1; and

FIGURE 3 is a view in section of the device of FIG- URE 1 taken along the lines 3--3 of FIGURE 1.

Referring now to the drawing, the circulation control device 10 is preferably comprised of an elongated frangible tube 12, which in its preferred embodiment is cylindrical, though it is understood that the device could be rectangular or polygonal in cross section. The elongated portion 12 may be made of any convenient frangible material, and in one illustrative embodiment, is made of pressed paper. At one end of the control device, a tapered nose member 14 is secured to the cylinder [12 and may be formed of any convenient heavy material which may be cut by the drill bit. In its preferred embodiment, the nose is formed of cement. At the end of the cylinder 12, opposite the nose 14, a cap of frangible material 16 is inserted in the cylinder after the circulation cont-r01 material 18 is inserted in the cylinder. This circulation control material may be in the form of large particles which could not otherwise be introduced into the bore hole. For example, the material may be wood chips, rags, fiber, or any other convenient material. The circulation control device is provided with a number of apertures 20 formed in the cylindrical portion 12 for the purpose of permitting the entry of drilling fluid and permitting the escape of any air entrapped in the device. Also advantageously, the rear cap 16 may have an aperture 22 therein to permit the escape of air and the entry of drilling fluid. Advantageously, the size of the nose cone 14 is such that the overall specific gravity is greater than unity, such that the device will sink to the bottom of the bore hole by the force of gravity.

In accordance with the method employed in controlling the circulation in the particular regions of the bore hole, one or more of the control devices 10 is introduced into the bore hole. These devices are permitted to sink to the bottom of the bore hole. The drilling string is then introduced into the bore hole and the drill bit lowered into contact with the device or the last of the devices and is actuated to fracture the frangible containers, and thereby release the circulation control material.

Although this method and apparatus has. been described in connection with the introduction of large-sized circulation control material, it is of course understood that it could be employed in the instance of small-size circulation control material when it is desired to reduce the amount of control material required by localizing the region into which the material is introduced. This method and apparatus is, of course, particularly advantageous in the insertion of circulation control material which would otherwise clog the passages in the drilling string if employed in the conventional manner by the introduction at the surface through the drilling string.

While I have shown and described one illustrative embodiment of this invention, it is understood that the principles thereof may be applied to other embodiments Without departing from the spirit and scope of this invention.

What is claimed is:

A bore hole circulation control device comprising an elongated rigid frangible substantially cylindrical container having an overall specific gravity greater than unity, particulate circulation controlling material in said container, a substantially conical member on one end of said container, said container having a plurality of fluid pressure equalizing passages therein, wherein said container is formed of laminated material and wherein said substantially conical member is formed of cementitious material.

References Cited in the file of this patent UNITED STATES PATENTS 1,609,153 Carter et al Nov. 30, 1926 2,139,929 Blow Dec, 13, 1938 2,267,833 tMcMahan Dec. 30,. 1941 2,352,805 Schenermann et a1. July 4, 1944 2,609,880 Dyer Sept. 9, 1952 2,768,693 Hughes Oct. 30, 1956 2,778,604 Reistle Jan. 22, 1957 

